R10 and C1 make this circuit a nice mosfet fryer... Those designs are really unreliable.
The only thing to blame about IRF540/640/9540/9640 is that they are employed as low-cost power devices in their linear region in too many poor and unreliable designs. Reliability is tricky to achieve because HEXFETs weren't intended for linear operation, but these transistors are fine anyway.
BTW: Any class D amplifier without suitable current limiting and power sequencing is likely to blow transistors from time to time...
The only thing to blame about IRF540/640/9540/9640 is that they are employed as low-cost power devices in their linear region in too many poor and unreliable designs. Reliability is tricky to achieve because HEXFETs weren't intended for linear operation, but these transistors are fine anyway.
BTW: Any class D amplifier without suitable current limiting and power sequencing is likely to blow transistors from time to time...